Escalating energy costs have lead to increased efforts in exploring more effective insulation materials for windows, houses, water heaters, as well as other appliances and equipment. In recent years, aerogels have been suggested as prospective insulation materials for these applications. Aerogels are a unique class of ultra-low-density (0.1-0.2 g/cc) materials with 90-99 percent porosity; the high porosity, intrinsic pore structure, and low density makes aerogels extremely valuable materials for these applications. Conventional aerogel preparation techniques involve the preparation of a gel that is subsequently dried under supercritical conditions. Monolithic aerogels prepared using these techniques disclosed in the literature are fragile and the preparation process involves complex time-consuming steps.
Alternatively, aerogel powder-fiber compacts (APFC) have also been suggested as prospective thermal insulation materials. APFCs are prepared by a process involving the prefabrication of several ingredients (aerogel powder, fibers, binders), which are later mixed together and compacted to form insulation boards or cloths. The preparation of APFCs, however, requires large amounts of aerogel powder and involves a significant number of steps in the fabrication process. Additionally, the insulating properties of the typical APFCs disclosed previously are inferior to those of the fragile, monolithic aerogels.
Related U.S. Pat. Nos. include: 2,808,338; 2,945,817; 3,629,116; 3,869,334; 4,402,927; 4,447,345; and 4,610,863. Related European patents include: EP 018,955 (1980) and EP 382,310 (1990). British patent application 2,141,418 discloses a process for the production of carbon containing materials having ultrafine grains. The patent further discloses producing a very dense body containing carbon by placing carbon fibers in a silica aerogel and chemically depositing carbon in the vapor phase into the silica aerogel to form a dense body with high thermal conductivity.